A known problem associated with rim fire ammunition used in AR15/M16 style firearms involves the spent casings becoming lodged within the upper receiver channels. Existing one piece charging handles further tend to not be fully closable when employed with modified action assemblies (receiver plate, reciprocating bolt, forward chamber adapter) installed within the upper receiver for receiving such as sub-caliber (e.g. rimfire) ammunition. Such existing charging handles tend only to retract rearwardly approximately half an extracting distance, such as required for removal of the action assembly, and in comparison to a range of motion associated with original manufacturer specified action assemblies such as employed with center fire cartridges.